Many sleep related respiratory conditions, for example, snoring, are caused by a blockage or partial blockage of the respiratory tract. As the blockage increases, hypopnea, or a reduction of air flow to the lungs, occurs. Apnea, or a temporary cessation of breathing, can occur when the airway becomes totally blocked. A person suffering from sleep apnea may have difficulty functioning during the day because of insufficient sleep caused by the apnea events. In severe cases, the person also can suffer from problems caused by reduced blood oxygen levels.
One form of treatment for severe snoring, hypopnea and sleep apnea involves the application of a breathing gas delivery system to the person's respiratory tract while sleeping. Sufficiently high positive airway pressure (PAP) is applied to the person's airway to prevent its collapse or blockage. The applied positive, pressure supplied by a breathing gas delivery system, is usually within a range of 3 to 20 cm H2O.
Referring now to FIG. 1, there is shown a typical known breathing gas delivery system 10. The breathing gas delivery system 10 comprises a control unit 12, a flexible tube 14, and a suitable device for injecting air into the user's nasal passages, such as a face mask 16. The face mask 16 is typically designed to cover the user's nose and/or mouth and forms an air-tight seal with the face of the user 18. The mask 16 preferably includes adjustable straps 20 and 22 for adjusting the tightness of the mask on the face of the user 18.
The control unit 12 includes a regulated blower (not shown) that supplies a flow of air to the face mask 16 via the flexible tube 14. The control unit 12 includes a first switch 24 for turning on the breathing gas delivery system 10. Typically, when the breathing gas delivery system 10 is initially turned on, the system supplies breathing gas at a comfortable lower pressure to the person while he falls asleep. The breathing gas delivery system then gradually increases the pressure of the supplied breathing gas to a prescribed therapeutic level. Accordingly, the control unit 12 may include a second switch 26 for controlling the time period for increasing the supplied breathing gas pressure.
The breathing gas delivery system 10 is calibrated following testing that is usually conducted at a sleep clinic. With proper use, the breathing gas delivery system 10 will overcome hypopnea and sleep apnea and allow the user to receive adequate sleep.
Some users, however, may experience difficulty or discomfort using their breathing gas delivery system and may terminate its use during the night, or even stop using the system entirely. Physicians, both for reasons of providing adequate treatment for the patients, and also for reason of medical reimbursements, need to verify that the systems are being used as prescribed and are providing effective relief for the patients. Accordingly, there is a need to assure that the patients are using the system in compliance with the prescribed instructions that are issued with the breathing gas delivery system.
To monitor compliance and to gauge the effectiveness of the prescribed treatment, many such systems are capable of storing usage information, including, for example, information regarding the number of events which are detected during each sleep session and the pressures being used. Such information can be stored in the system over multiple sleep sessions, extending, in some cases, for many weeks. To read the information, a read-out of some sort may be provided that can be read to the doctor's office over the phone. However, this method of information exchange is susceptible to falsification, for example, by a patient who is embarrassed that the machine is not being used in the prescribed manner, or by a doctor's office to ensure reimbursement when such reimbursement may not otherwise be appropriate. To avoid such situations, it would be desirable to provide a method of exchanging such information that is resistant to tampering, but which may still be transferred person-to-person via a telephone.